Before the advent of litters, pet owners had relegated pets to outside the home for lack of an area for taking care of pet excrement. Litters allow pets to take care of waste functions and live inside the home. Housebroken animals, such as cats, are trained into the habit of urinating and defecating in a specially provided litter box. Similarly, untrained and caged animals, such as guinea pigs, urinate and defecate on the floor of their cage, often in approximately the same floor area of the cage. Consequently, pet owners, homeowners, veterinarians and laboratory personnel have added liquid-absorbing materials to the litter box or cage to collect the urine and feces.
The most commonly used litter box liquid-absorbing materials are inexpensive clays, such as calcined clays, that are safe and non-irritating to the animals, and that absorb substantial amounts of liquids. Other porous, solid litter box absorbent materials, that are used alone or in combination, include straw, sawdust, wood chips, wood shavings, porous polymeric beads, shredded paper, sand, bark, cloth, ground corn husks, and cellulose. Each of these absorbent materials has the advantage of low cost. The entire contents of the litter box including the soiled and unsoiled liquid-absorbing materials will eventually be removed because of the offensive odor caused by the absorbed urine and feces.
Most litters do not adequately control the odor associated with urine. The simple absorption of liquid, which litters typically provide, does little to counteract the growth of odor-causing bacteria. Currently clay soils or comminuted rocks, e.g. the sodium bentonites, are used in an attempt to improve litter compositions. Sodium bentonites absorb liquid waste such as urine, and may also absorb some of the odor associated with the liquid waste, as the material binds amine compounds in the “face sites” of the clay interlayers. Plant-based litters, such as those made from wood chips or corn, can also absorb liquid waste, and be made disposable with the aid of clumping agents, but, again, litter box odor remains. This is because a significant contributor to “litter box smell” is the odor resulting from bacterial action on “aged” urine after three or so days in a litter box. In some cases, some of the urine can even collect and pool at the bottom of the litter box making an excellent breeding ground for bacteria. It is this bacteria from “old urine” in the litter box that most litters do not cover up well, and which is particularly troublesome to consumers.
Moreover, traditional plant-based or clay-based litters that are composed of sodium bentonites or other materials do not address the issue of fecal odor. Fecal odor differs from urine odor in that the odor is produced immediately at the time of defecation. Materials in fecal odor that carry an especially strong impact include butyric acid, p-cresol, skatole, and dimethyltrisulfide.
Furthermore, these traditional litter compositions are often formed from coarse granules, such that the granule's irregularity in both shape and size creates tracking by animals after usage, and dust formation that is associated with granule bumping.
There is also a concern of the rising cost of litter ingredients due to limited resources or unexpected high demands. For example, guar gum, a clumping agent, is also used in hydraulic fracturing (“fracking”) to adjust fracturing fluid viscosity. The recent popularity of fracking has driven up the cost of guar gum dramatically, forcing other industries to search for an alternative.
Various attempts to address the above issues are known in the art. For example, U.S. Pat. No. 8,074,604 to Swank teaches an animal litter that includes a sorbent material that is composed of granule particulate, which is able to pass a −20 screen sieve. The sorbent material is combined with a binder such that greater than 90% of the granules have a size of between −5 and +60 screen sieve. The Swank granules also have an oil coating. The feedstocks operative in the Swank invention include corncob, bentonite, diatomaceous earth, attapulgite, montmorillonite, cellulosic plant stalks, husks and hulls, and combinations thereof.
US Patent Application Numbers 2009/000562 and 2012/0012064 to Jenkins et al. teach a waste encapsulating animal litter that encapsulates the solid and liquid animal waste within a shell that has a thickness of at least 1 mm, and wherein the litter comprises a water reactive polymer as a binder, an acidic solid material, and a carbonate-containing or percarbonate-containing solid material.
U.S. Pat. No. 5,101,771 to Goss teaches an animal litter made from clay materials and a combination of hydroxypropylmethylcellulose, a clumping agent, and mineral oil, which acts as a dedusting agent.
The above references teach improvements of the traditional litters and disclose modifying base particle sizes and the use of additives such as binders and acids. However, these references only address one of many concerns and do not present a full solution to the challenges presented in finding a litter which will satisfy consumer needs. Further improvements must be implemented to effectively reduce tracking and odors, while yielding a litter which may be economically manufactured.